One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,11)(8,9)(10,12)(14,15)(16,20)(21,22)(23,24)(25,28)(26,27) involution — undirected(5,7)(6,10)(8,11)(9,12)(13,14,17,15)(16,18,20,19)(21,23)(22,25)(24,26)(27,28)(7,12)(10,11)(13,14,17,15)(16,19,20,18)(21,24,27,25)(22,28,26,23)(1,2)(3,4)(5,8,9,6)(7,10,12,11)(13,15,17,14)(16,19,20,18)(21,25,27,24)(22,28,26,23)(5,7)(6,11)(8,10)(9,12)(13,16)(14,18)(15,19)(17,20)(21,26,27,22)(23,24,28,25)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.